7193 tube wiring

Dave C

Super Member
I'm installing 2 7193 tubes in my 300B build. The anode and grid comes out the two top caps on these tubes. My Question is should I use shielded wire to these top caps or is it OK to not shield the conductor? You can see the tube at this address. http://www.r-type.org/exhib/aaa0163.htm Your tips and experience on hookup?
 
Wire with a shield generally has a higher capacitance than unshielded. If the tube has it's sensitive regions teased out like that, why not try to maximize the benefit? I'd try to run unshielded wire as far from potential noise sources as possible, and see if a hum-free implementation could be achieved.
 
Make sure the insulation resistance of the wire that you do use can sustain the expected voltage plus a safety margin.
 
Fred,
I looked around and found a solid piece of wire rated for 600V, I take that to mean the insulation is rated at 600V. Problem with shielded wire is that it isn't rated for voltage as far as I've seen. I also want to use solid conductor wire for this. The tubes look like 300V at 11ma. so current isn't an issue but voltage might be.
Squidward,
I never thought about capacitance in shielded wire. Thanks for your input on that. That wire is about 4" long from the input to the cap on the first tube so I don't think that will be to much to cause trouble but I might see if I can measure anything in the wire.
As always guys if you've "been there, done that" I like to hear about it!
Dave
 
"As always guys if you've "been there, done that" I like to hear about it!
Dave"

Dave I've never used any "Special" wire to hook up top caps with, be it
the input "grid" or the hv "plate" and if your talking about 300v I wouldn't
worry about voltage rating either, over say.. 550v I'd be wondering about
the voltage but anything below that I'd have no problem.

Cheers!
 
I would not worry about the plate cap. But the grid may or may not benefit from shielded wire. Remember, many 30s radios had the grid wire unshielded. However, some ran the wire inside of the tube shield...
 
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